On Wed, 30 Nov 2005 03:02:10 GMT, "W. Watson"
wrote:

Phil Wheeler wrote:

W. Watson wrote:


I'll continue to experiment, but so far not so good. Comments?


As others have said, you should try to attenuate the noise at its
source. If it is radiated, you need a better PSU. If it is coming out
on the PCs AC line, line filters might help.

If the PC and KGO are not in the same direction, some sort of
directional antenna might help.

Of course, the ultimate solution would be to move to SF and get a really
big signal. But there are problems with that, too: I live abt 3-4 miles
west of KNX (50 KW, 1070 KHz) and my problem is avoiding it, not making
it stonger

Phil
Yes, I've had that experience with close stations. You can probably listen
to it through the bed springs. :-)

Attempts to shield the AC with the RS ferrite block and a barbell weight
failed. See comment about household circuit dependency in my just posted
responses above yours.

Wayne,
You may wish to get one of those $5 circuit analyzers from your local
Lowe's/Home Depot/Tools R Us (yes, I realize this probably means a
drive to Grass Valley) and check for open ground connections on all
your sockets. I had grounding issues at my home and after getting a
shock while adjusting the hot water in the shower brought in an
electrician. He found many problems such as the hot and return
shorting on the bathtub (behind the wall of course where it can't be
seen) and most of my outlets did not have a ground. Had the house
re-wired and it got a bit more RF friendly - hope you find your issue
and don't have to rewire the house.

BTW, Nevada City is a nice place to call home - if you bump into
Mayor Arnett tell him that Howard from LA says hi.

Howard

W. Watson wrote:
Cecil Moore wrote:
Why do you think that's a radio problem? :-)

When I turn the computer off, the radio station noise drops
dramatically. It doesn't matter if I use AC or DC. I can detect the
large noise change in my car from the garage.

That sounds like a computer problem, not a radio problem.
What am I missing?
--
73, Cecil http://www.qsl.net/w5dxp

Dave Platt wrote:
In article t,
W. Watson wrote:


I tried the RS ferrites and they made no change. I even took barbell weights
and put them on the AC line of the PC. Zippo. If I hadn't already spent $60
for the new PSU six weeks ago, I might think of buying a much better one.


Ferrites clamped around the power cable will help with common-mode RF
noise. They won't do anything to help cancel out differential-mode
noise.

Differential mode radiation is almost never a problem in situations like
this. The differential mode component of the noise, by definition, is
from equal and opposite noise currents on the two conductors (of the
power line, for example). For this mode, the conductors comprise a
transmission line, and radiation will be extremely small because the
fields from the two very close and parallel conductors are equal in
magnitude and opposite in direction.

Ferrites are a good suggestion, but the ones commonly used for RFI
suppression are of a ferrite type which doesn't have an awful lot of
attenuation as low as the AM broadcast band. Best would be some
Fair-Rite 70 series, or other ferrite with an initial permeability of
several thousand. Best would be to get a large core and wrap multiple
turns on it with the power cord, as close to the PC as possible. This
way, you get a lot more impedance than clamping cores onto the wire,
since the impedance is proportional to the square of the number of
turns. That is, 10 turns on a single core gives you the same impedance
as 100 of the same cores clamped onto the cable.

It'd probably be beneficial for you to try to get a robust powerline
noise filter. These will filter out both common-mode noise, and
differential noise as well.

A good power line filter isn't a bad idea, but differential mode
filtering won't make any appreciable difference.

Unfortunately, it's possible that the new power supply is radiating RF
directly, rather than feeding it back into the mains. If so, nothing
other than replacing it, or switching to a PC case with better
shielding, is likely to help the problem.

To radiate any significant amount of energy requires some sort of
antenna, so a power supply won't radiate much on its own. The trick,
then, is to prevent the noise from getting from its source to the
antenna. The most likely antenna is the power line, but any other wires
connected to the computer can also serve this function. I'd start by
disconnecting everything from the computer except the power line,
getting the noise down with ferrites or a power line filter, then
connecting one thing at a time and applying ferrites to the other wires
as required. If wires inside the computer are acting as the antenna, the
computer box should contain the noise to a high degree -- if you still
have noise with only the power line connected and filtered, check the
integrity of the computer case. Look for any seams that don't have good
metal-to-metal contact between pieces.

Roy Lewallen, W7EL

On Wed, 30 Nov 2005 03:44:17 GMT, "W. Watson"
wrote:

If so, how do I track it down?

Hi OM,

You have already related other experience where you shared the same
circuit as a noisy source (sharing the same circuit is easily
identifiable as being on the same breaker). Moving to another circuit
can be a solution. If it provides relief, then noise was coming by
conduction (through the wires) rather than radiation (over the air).

Insofar as your specific weather related symptoms, this is usually
related to a loose and corroded ground connection. The first place to
start is with your panel's service ground. If you have other ground
rods, then check them and INSURE they are also connected to the
service ground.

In your shack, do not daisy-chain grounds - use a star configuration.
However, you will probably still have mixed grounds with equipment
interconnections (and some of them are obvious and in your face and
are still invisible). That is OK if you also have the individual
equipments grounded in that star configuration. One of those
invisible gotchas is the equipment interface to a computer, with a
dial-up modem, its connection to the phone line and its own ground
(if in fact it exists). This ground path is one you stare at every
day and never see - unless lightning is looking for ground in through
it and into your shack.

To "track it down" requires that you pull every plug, break every
breaker and listen (you will need a battery powered, ungrounded
receiver that exhibits the problem to do this). Replace each one at a
time until you re-achieve your problem - take one step back and focus
there.

73's
Richard Clark, KB7QHC

Mike Coslo wrote:

W. Watson wrote:

Michael Coslo wrote:

W. Watson wrote:

I bought this antenna on a 30 day trial, and just got it about 12
hours ago. So far I'm not at all impressed. I live about 150 miles
from an AM station, at 810, in the SF/SJ Bay Area, which has a
marginal signal, but usually listenable. Putting a new PSU in a PC
about a month ago increased the noise in AM radios 70-100' from the
PC to an almost unacceptable level. I had hoped the antenna would
boost the signal enough to knock down the noise. There are times
when I can get a good signal from the station, but certainly less
frequently than before.




Any rf noise put out by the computer ps is going to be picked up
by your antenna as well as the radio station you are trying to hear.
So a better antenna (if your new one is indeed better) wil just pick
up stronger power supply noise. It's moslty a null situation.

What you need to do is get that power supply fixed or replaced

- 73 de Mike KB3EIA -

I think the only solutions to the PSU problem is to buy a much better
one. As I mention above, that's probably a losing proposition. I doubt
after 6 weeks they would take it back. It might be worth a try though.
Note my comment above to someone a few moments ago that this seems to
be a household circuit dependent problem. Another PC in the same room
works fine until I plug it into the socket that I first noticed the
problem.



Hmmm, just maybe, you might be able to ditch it as a warranty item.
Dunno tho' as it will depend on the outfit that sold it to you. I don't
know if you are a Ham or not, but if you are, you might play the part 15
card, as they are required to not interfere. I suspect that a 160 meter
rig might catch the same interference.

It is kind of a drag though, since IIRC a noisy switcher Power
supply is hard to fix. Good luck!

- 73 de Mike KB3EIA -
I'm tempted, but somehow your message gave me another idea. I think I'm
going to take the PC to an entirely different location miles from here and
see if get the same problem.

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Traveling in remote places in the winter. What's the best
tool to carry with you? An axe.
-- Survivorman, Discovery (SCI) Channel

Web Page: home.earthlink.net/~mtnviews

Howard wrote:

On Wed, 30 Nov 2005 03:02:10 GMT, "W. Watson"
wrote:


Phil Wheeler wrote:


W. Watson wrote:


I'll continue to experiment, but so far not so good. Comments?


As others have said, you should try to attenuate the noise at its
source. If it is radiated, you need a better PSU. If it is coming out
on the PCs AC line, line filters might help.

If the PC and KGO are not in the same direction, some sort of
directional antenna might help.

Of course, the ultimate solution would be to move to SF and get a really
big signal. But there are problems with that, too: I live abt 3-4 miles
west of KNX (50 KW, 1070 KHz) and my problem is avoiding it, not making
it stonger

Phil

Yes, I've had that experience with close stations. You can probably listen
to it through the bed springs. :-)

Attempts to shield the AC with the RS ferrite block and a barbell weight
failed. See comment about household circuit dependency in my just posted
responses above yours.


Wayne,
You may wish to get one of those $5 circuit analyzers from your local
Lowe's/Home Depot/Tools R Us (yes, I realize this probably means a
drive to Grass Valley) and check for open ground connections on all
your sockets. I had grounding issues at my home and after getting a
shock while adjusting the hot water in the shower brought in an
electrician. He found many problems such as the hot and return
shorting on the bathtub (behind the wall of course where it can't be
seen) and most of my outlets did not have a ground. Had the house
re-wired and it got a bit more RF friendly - hope you find your issue
and don't have to rewire the house.

BTW, Nevada City is a nice place to call home - if you bump into
Mayor Arnett tell him that Howard from LA says hi.

Howard
Ah, you know about us. I'm not a ham, but I will be speaking to our local
club in January about radio astronomy. I used to have my hair cut by the
former mayor. I'll have to ask my present barber if he frequents her shop.
Maybe he attends the ham meetings. I only go to them when I want to promote
RA, which has been 3 times. Although I went a few weeks ago to find out if
anyone had a Icom R7000 rcvr. No luck. However, my opportunity to buy one
disappeared within a few days of that meeting.

I may have one of those analyzers here somewhere. Lowe's is a long way from
here, but we have one very good hardware store that would be a good candidate.

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Traveling in remote places in the winter. What's the best
tool to carry with you? An axe.
-- Survivorman, Discovery (SCI) Channel

Web Page: home.earthlink.net/~mtnviews

Cecil Moore wrote:

W. Watson wrote:

Cecil Moore wrote:

Why do you think that's a radio problem? :-)


When I turn the computer off, the radio station noise drops
dramatically. It doesn't matter if I use AC or DC. I can detect the
large noise change in my car from the garage.


That sounds like a computer problem, not a radio problem.
What am I missing?
Probably nothing. However, I'd be willing to bet that I wouldn't have this
problem if I were 100 miles closer to the radio station. The Crane device
has been so ineffective its baffling as an issue aside from the one about my
radio. I built an FM signal booster when I was 14 that showed more promise.
Well, I've got 28 more days to return it. If it shows nothing more, I will
be out about $7.00 for return postage--rental fee?

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Traveling in remote places in the winter. What's the best
tool to carry with you? An axe.
-- Survivorman, Discovery (SCI) Channel

Web Page: home.earthlink.net/~mtnviews

W. Watson wrote:
Cecil Moore wrote:

W. Watson wrote:

Cecil Moore wrote:

Why do you think that's a radio problem? :-)



When I turn the computer off, the radio station noise drops
dramatically. It doesn't matter if I use AC or DC. I can detect the
large noise change in my car from the garage.



That sounds like a computer problem, not a radio problem.
What am I missing?

Probably nothing. However, I'd be willing to bet that I wouldn't have
this problem if I were 100 miles closer to the radio station.

Absolutely. If the station signal is relatively stronger than the
computer noise, the computer's RFI will not be so much an issue. Right
now, they are about the same strength. Moving the computer will probably
help a lot.

Just out of curiosity, what is the frequency of the station you are
trying to recieve?

And while we are at it, is the noise on the radio in just one spot, or
is it on pretty much the whole band?

- 73 de Mike KB3EIA -

On Wed, 30 Nov 2005 13:26:37 GMT, "W. Watson"
wrote:

W. Watson wrote:
I'll continue to experiment, but so far not
so good. Comments?

I would like to relate my experience. As you
did, I carefully selected a new computer case
and power supply from the stock at redacted,
paying careful attention to the FCC logo on the
power supply. After moving the mother board
over and turning it on, it completely wiped
out reception of the local 5kW station on 550 kHz.
Fortunately, I had picked up a couple of surplus
Corcom line filters (Model # 10ESK7)at a local
hamfest three years earlier (it pays to collect
junk). I spliced it into the computer power
cord and it cured the problem completely.

I don't have any experience with the Radio
Shack line filter (Catalog # 15-1111), but it
looks like it might do the job for you.

73, Jim, K7JEB

Michael Coslo wrote:

W. Watson wrote:

Cecil Moore wrote:

W. Watson wrote:

Cecil Moore wrote:

Why do you think that's a radio problem? :-)




When I turn the computer off, the radio station noise drops
dramatically. It doesn't matter if I use AC or DC. I can detect the
large noise change in my car from the garage.




That sounds like a computer problem, not a radio problem.
What am I missing?


Probably nothing. However, I'd be willing to bet that I wouldn't have
this problem if I were 100 miles closer to the radio station.


Absolutely. If the station signal is relatively stronger than the
computer noise, the computer's RFI will not be so much an issue. Right
now, they are about the same strength. Moving the computer will probably
help a lot.

Just out of curiosity, what is the frequency of the station you are
trying to recieve?

And while we are at it, is the noise on the radio in just one spot,
or is it on pretty much the whole band?

- 73 de Mike KB3EIA -

810 AM, KGO. Good question about the width of noise. Let me check ...
I just took the radio out near the PC, and operated it on battery.

With the PC on, and moving in steps of 10KH from 700 to 900:
noise almost everywhere execpt at 830, which is about 3 miles from my house
and over a hill.

With the PC off, some noise everywhere, but 710 (station and somewhat
noisyg), 740 (station and somewhat noisy but not bad-- KCBS inSF, CA), 810
(clean), 840 (station and somewhat noisy). In other words things improved
quite a bit.

--
Wayne T. Watson (Watson Adventures, Prop., Nevada City, CA)
(121.015 Deg. W, 39.262 Deg. N) GMT-8 hr std. time)
Obz Site: 39° 15' 7" N, 121° 2' 32" W, 2700 feet

Traveling in remote places in the winter. What's the best
tool to carry with you? An axe.
-- Survivorman, Discovery (SCI) Channel

Web Page: home.earthlink.net/~mtnviews